This invention generally relates to conveyor assemblies and linear slides used in manufacturing assembly lines, and more particularly, to mechanisms of providing linear as well as selective rotary motion for articles which are being conveyed down an assembly line.
Conventional conveyor assemblies typically include a number of conveyor links which are pivotally attached to each other and which follow a linear path along the assembly line. The conveyor links typically include a table top upon which articles are placed for movement down the assembly line. In many operations it is desirable to rotate the article on the table top a predetermined radial distance, such as 90.degree. or 180.degree., at particular work stations. Prior art systems typically use an external positioning mechanism, such as a robotic arm, which grasps the article, lifts the article off the table top, rotates the article a predetermined radial distance, and then replaces the article back in its original location on the table top. Such external positioning machines are expensive and their use greatly complicates the assembly line process.
An important aspect of this invention therefore lies in providing an actuator member which carries a table top and is capable of providing selective rotary movement of the table top as the actuator member moves in a linear direction along a conveyor line without the need for expensive and cumbersome external positioning machines. The actuator member is attachable to a conventional conveyor link and includes a table top for supporting an article. The actuator member is provided with a follower wheel and actuation means are provided on the follower wheel for engaging a stationary cam and either preventing rotary motion of the table top or rotating the table top a predetermined radial distance. The inventive actuator member is highly advantageous in that it can be retrofitted onto existing conveyor systems and eliminates the need for external positioning machines which have been used in the past.
In brief, the actuator member includes a platform housing which can be attached to a standard conveyor link. A follower wheel is rotably mounted in the housing and includes a table top for supporting an article. The follower wheel is provided with actuation means for engaging a stationary cam and selectively preventing rotation of the table top or rotating the table top a predetermined radial distance as the actuator member progresses down the conveyor line. The stationary cam runs parallel and adjacent to the conveyor line and includes dwell portions and index portions which are selectively positioned for engaging the actuation means and either preventing rotation of the table top when the actuation means engages a dwell portion or rotating the table top a predetermined radial distance when the actuation means engages an index portion.
In one embodiment of the invention, the follower wheel includes an upper disk-shaped plate which includes the table top, a middle disk-shaped plate, and a lower disk-shaped plate. The upper plate is separated from the middle plate by a peripheral slot, and the middle plate is separated from the lower plate by a second peripheral slot. A plurality of rotably mounted cam followers are mounted in the first and second peripheral slots and extend generally in a perpendicular direction with respect to the platform housing. For use with this construction, the stationary cam includes a first cam portion which is positioned to engage the cam followers in the first peripheral slot of the follower wheel and a second cam portion which is positioned to engage the cam followers in the second peripheral slot.
Such a dual level or conjugate cam construction is highly advantageous in that the two levels of engagement between the actuation means and the stationary cam provide smooth rotary motion of the follower wheel with little backlash and provides for greater accuracy in rotating an article a predetermined radial distance than prior art external positioning systems. In the embodiment described in the specification, the index portion comprises a projection member and a concave portion combination provided on the upper stationary cam portion and an oppositely orientated concave portion and projection member provided on the lower stationary cam portion. The cam followers are provided on the follower wheel in pairs in which one of the cam followers is provided in the upper peripheral slot of the follower wheel and the other cam follower is provided in the lower peripheral slot of the follower wheel. Accordingly, when a pair of cam followers engage the upper and lower portion of a rotation cam, one cam follower engages a projection member and the other cam follower engages the concave portion to provide the follower wheel with smooth rotary motion.
The inventive actuator member is usable in different types of conveyor systems which include conveyor means for supporting the actuator member and for moving the actuator member along a path that includes at least one linear path. The stationary cam is mounted so that it extends in a longitudinal direction parallel and adjacent to the linear path of the conveyor means and is provided with selective dwell portions and index portions for affecting the desired movement of the follower wheel and table top. In one embodiment, the conveyor means comprises a continuous conveyor belt formed from a plurality of pivotally connected conveyor links, and each conveyor link is provided with an actuator member which has its platform housing fixedly mounted thereto. The conveyor system includes guide means at the nonlinear portions of the conveyor system for engaging the follower wheels of the actuator members and preventing rotary motion while said actuator members pass through said nonlinear portions of the conveyor system. The follower wheels may be provided with flat portions on the outer peripheral edges of the middle plates of the follower wheels for engaging the guide means.
In another embodiment, the conveyor means may take the form of a linear slide having a shuttle which is positioned to move along a linear path. The actuator member in that case is fixedly mounted to the shuttle for movement along the linear path. The stationary cam is positioned parallel to and adjacent to the linear path and includes dwell and rotation cams for engaging the follower wheel.
Other objects, features, and advantages of the invention will become apparent from the following description and drawings.